DE1803357A1 - Acid electrolyte to achieve shiny and smooth zinc coatings - Google Patents

Description

Dipl.-Ing. Egon Prinz ·, rm λ. -l. ι r, r <^ Dr. Gertrud Hauser eooo Mü "ch." 60th October 16, 1968 DipK-Ing. Gottfried Leiser Patent attorneys I O U O O D /

Tel «gramm6i Labyrinth Munich

Telephone 83 15 IQ Poiteheckkontoi Mönchen 117078

COMPAGNIE DES COMPTEURS

3, rue Dosne

Paris ^16e / France

Our reference: 0 2562

Acid electrolyte to achieve shiny and smooth zinc coatings

As a rule, electrolytic zinc deposits are obtained from cyanide baths with good penetration properties, the addition of organic compounds enables shiny feathering to be achieved. Own these baths but practically no leveling ability at all. and only give a moderate yield. Besides that The problem of residual water arises for these baths.

If you want to increase the rate of precipitation, acidic baths based on pluoborate are used or - sulfate; however, these baths do not make it possible to obtain glossy precipitates and have only one very low penetration.

The zinc baths based on pyrophosphate have the Downside to be expensive and they have to be at increased

Dr Ha / Eü 909821/1067

Temperature.

Electrolysis on the basis of zincate in turn offer Difficulties due to anodic polarization and the formation of anode sludge.

The present invention is characterized by Use of an acidic electrolyte, which, however, results in shiny and leveled zinc deposits enables; In addition, the electrolyte is completely non-toxic and can be operated at room temperature.

The acidic electrolyte according to the invention is characterized in that it contains at least the following basic components:

a zinc salt, for example zinc sulfate, an alkali metal salt or an ammonium salt, for example " Ammonium sulfate, a (dhiosemicarbazone compound of the general formula

CS

^ NH - N = OH - R, on which a thiourea group

NH ₂ - CS - NH ₂ ''

sits, and in which the radical R is preferably the carbon chain of a phenol aldehyde or its Is oxide ether derivatives.

The urea group can also be bound to the phenol aldehyde before conversion into the Ihiosemi: carbazone compound,

909821/1067

The use of a thiocarbamic acid condensed with a phenol aldehyde also falls within the scope of Invention, wherein the thiourea group is either at the acid or the aldehyde can sit.

The complex obtained by the reactions described is hereinafter referred to as the "primary brightener" designated.

It was found that the expansion of the luster and the glossiness of the precipitate still through single or simultaneous use of the following organic compounds is improved;

an aliphatic diamine, for example ethylenediamine, Propylenediamine, di-ethylenediamine

Hexame thy1ente tramin

Anionic surfactants, for example

Alcohol sulfates with 8 to 12 carbon atoms,

Nonionic surfactants containing 10 to 30 molecules of ethylene oxide

Cationic surfactants obtained by condensation of fatty acids with a diamine or Triamine

Polyglycols or polyalcohols such as glycerine

An imidazole compound, particularly that obtained by the action of an amine on glyoxal,

909821/106 7

for example through. Action of 1 mole of glyoxal OHO-CHO on 1 "mole of diaethylene triamine, the reaction taking place at moderate temperature (40-80 ° C) in an aqueous medium \ the diaethylene triamine can also be replaced by the ethylene diamine or the diaethylene diamine.

The addition of this compound increases on the one hand the glossy surface and on the other hand sets the consumption of primary Brighteners down; it has such an effect that it even in the absence of the primary brightener can cause a glossy effect.

Finally it was found that the addition of complexing substances, for example ethylenediaminetetraacetic acid or its salts, improves the anodic yield and the stability of the electrolyte »

The following are non-limiting exemplary embodiments for electrolytes composed according to the invention

example 1

100 to 150 g / l zinc sulfate · 7 H ₃ O

25 to 50 g / l ammonium sulfate

5 g / l ethylenediamine

5 g / l hexamethylenetetramine

10 g / l sodium N-octyl sulfate

0.5g / l primary brightener

0.3 g / l of an imidazole compound

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Example 2

up to 150 g / l zinc sulphate · 7 H ₂ O "up to 50 g / l ammonium sulphate 20 g / l citric acid 20 g / l hexamethylenetetramine 10 g / l sodium N-octyl sulphate 0» 5g / l primary brightener up to 3 g / l glycerine

In game 3

Corresponds to Example 2, except that the salt of the alcohol sulfate is replaced by 2 g / l of a non-ionic Wetting agent is replaced with 30 C ^^ O groups in the molecule,

Example 4

up to 150 g / l zinc sulphate · 7 H ₂ O 50 g / l ammonium citrate 10 g / l hexamethylenetetramine 1 g / l cationic, dibasic or polybasic, surface-active agent 10 g / l sodium U-octyl sulphate 0.5 g / l primary gloss agent

Example 5

up to 150 g / l zinc sulphate · 7 H ₂ O up to 50 g / l ammonium sulphate

20 g / l hexamethylenetetramine

5 g / l disodium salt of ethylenediamine tetra-

acetic acid

10 g / l sodium N-octyl sulfate 0.5g / X primary brightener

909821/1067

Working conditions of these baths: _

pH: 4 to 4.5 Temperature: 3O ⁰ C maximum, preferably 15 to 22 ⁰ G

2 current density; O "2 to 5 amps / dm Cathodic ^ agitation

909821/1067

Claims (3)

Dipl.-Ing. Egon Prince. Dr. Gertrad Hauser * °°° Munich eo, 13th Dezenp Dlpl.-Ing. Gottfried Leiser Er ".b.re.r, tra, .e if" 1 ^ '' Patentanwälte 1 8 Q 3 3 ü / Telegrams ι Labyrinth Mönchen Telephone: 83 15 10 Postal check account: Munich 117078 P 18 03 357.3 Compagnie des Compteurs Unser Characters: 0 2562 claims 1. Acid electrolyte to achieve zinc precipitates with strong gloss and good leveling, characterized in that it has at least the following Basic ingredients contains: a zinc salt, for example zinc sulfate, an alkali metal salt or an ammonium salt, for example ammonium sulfate, a thiosemicarbazone compound of the general formula - N = GH - R, on which a thiourea group - CS - NH sits, and in which the radical R is preferably the carbon chain of a phenol aldehyde or its ether oxide derivatives and / or an imidazole compound. 909821/1067 Dr Ha / he 2. Electrolyte according to claim 1, characterized in that that the thiosemicarbazone compound is a thiocarbamic acid condensed with a phenol aldehyde. 3. Electrolyte according to one of the preceding claims, characterized in that the electrolyte is still individually or in various combinations contains: an aliphatic diamine Hexamethylenetetramine an anionic, non-ionic or cationic surfactant a polyklycol or a polyalcohol 90982 1/106 7